Method and apparatus for processing optical signals with supergratings

ABSTRACT

An optical component including at least one optical supergrating is provided. The optical supergrating includes a quantized refractive index profile adapted to exhibit a finite plurality of refractive indexes; which in turn are adapted to generate a reflectance spectrum in at least one spectral band corresponding to a Fourier transformed analog refractive index profile.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a divisional of co-pending U.S. patentapplication Ser. No. 10/188,530, entitled “METHOD AND APPARATUS FORPROCESSING OPTICAL SIGNALS WITH SUPERGRATINGS”, filed Jul. 3, 2002,which application claims benefit under 35 U.S.C. §119(e) to U.S.Provisional Patent Application Ser. Nos. 60/302,904 and 60/393,209,filed Jul. 3, 2001 and Jul. 1, 2002, respectively, which applicationsare incorporated herein by reference in their entireties.

TECHNICAL FIELD

The present invention relates generally to processing optical signals,and more particularly to routing, filtering and detecting opticalsignals.

BACKGROUND OF THE INVENTION

Gratings are optical devices used to achieve wavelength-dependentcharacteristics by means of optical interference effects. Thesewavelength-dependent optical characteristics can, for instance, serve toreflect light of a specific wavelength while transmitting or refractinglight at all other wavelengths. Such characteristics are useful in awide range of situations, including the extraction of individualwavelength-channels in Wavelength Division Multiplexed (WDM) opticalcommunication systems, or providing wavelength-specific feedback fortunable or multi-wavelength semiconductor lasers. Gratings are usuallyimplemented by modulating (varying) the effective index of refraction ofa wave-guiding structure. These changes in index of refraction causeincident light wavelengths to be reflected or refracted: in the case ofan abrupt interface between two index values, light incident directly onthe interface is reflected according to the well-known Fresnelreflection law.

The term “multi-wavelength grating” generally refers to a grating thatis capable of exhibiting optical characteristics at a number ofwavelengths. For example, a multi-wavelength grating may be a gratingthat reflects light at several select wavelengths (which may correspondto specific optical communication channels), yet is transparent to lightat other wavelengths. In some situations, however, there is a need toset the optical characteristics for a continuous range of wavelengths,rather than at specific wavelength values; for example, when using anoptical grating to compensate for the unevenness of optical gainprofiles in laser cavities and optical amplifiers. However, achievingthis requirement for a continuous range of wavelengths is difficult tomeet with traditional grating technologies.

Similarly, a range of optical wavelengths may be used where manycommunication channels are encoded into a single optical cable byutilizing different wavelengths of light; this is more commonly known asWavelength Division Multiplexing (WDM) technology. Periodic gratings areoften used to separate or process these channels. However, periodicgrating technologies process one wavelength, forcing devices intended toprocess multiple wavelengths to employ multiple single-wavelengthperiodic gratings. This is not an attractive solution because, on top ofthe additional losses that each grating creates, even a single gratingoccupies a considerable amount of space by today's standards ofintegration and miniaturization. It is thus desired to have a singledevice capable of processing several wavelengths in a space-efficientmanner.

In the field of semiconductor lasers, the output wavelength ofsemiconductor lasers is largely determined by the presence of “feedbackelements” around or inside the laser gain section, which act to reflectlight at the desired wavelength back into the laser. Formulti-wavelength operation, multi-wavelength feedback is needed. Again,single-wavelength grating technology can only address this demand with acascade of simple gratings, leading to the same (if not more notable)loss and space problems mentioned above.

In the field of optical transmission, it is well known that opticalnetworks must contend with a property known as dispersion. This propertyarises from the wavelength-dependence of effective index, which in turnproduces a wavelength-dependent group delay spectrum for a given typeand length of optical fiber. Since an optical pulse always possessessome spectral width, this wavelength-dependence leads to differentretardation of various spectral components of the optical pulse, therebyleading to its spread in the spatial domain. This spread directlyimpedes the operation of the optical network. Some forms of dispersioncan be corrected for with single-wavelength gratings, but only on achannel by channel basis. More complicated forms of dispersion such asdispersion slope cannot be suitably corrected by single-wavelengthgratings at all.

One such single-wavelength grating device is a Bragg Grating. The BraggGrating consists of a periodic variation in refractive index and acts asa reflector for a single wavelength of light related to the periodicity(known as pitch, A) of the index pattern; and is frequently used in bothsemiconductor systems and fiber-optic systems. In practice, the BraggGrating can usually reflect at several wavelengths, corresponding toovertones of its fundamental pitch; however, these higher-orderwavelengths tend to be at quite different spectral regions than that ofthe fundamental wavelength, thus not making the Bragg Grating useful asa multi-wavelength reflector. Moreover, these higher-order wavelengthscannot be tuned independently of one another.

Other multi-wavelength grating technologies include: analog superimposedgratings, Sampled Gratings (SG), Super-Structure Gratings (SSG), ChirpedBragg Gratings, Dammann Gratings, Arrayed Waveguide Gratings (AWG),Echelle Gratings and Binary Superimposed Gratings (BSG).

Analog superimposed gratings are a generalization of the Bragg Gratingand are rooted in a principle of superposition: a grating profileconsisting of the sum of the index profiles of single-wavelengthgratings reflects at all of its constituent wavelengths. Such a gratingrelies on an analog index variation, that is, a refractive index thatchanges continuously along the grating length. However, it is difficultto inscribe strong analog gratings using the well-known photorefractiveeffect, since the change of index under illumination varies non-linearlywith stronger exposures, making the writing process difficult insemiconductors where surface relief gratings are used. It is also verydifficult and generally impractical to reproducibly etch analog featuresinto the surface of the semiconductor. The latter difficulty broughtabout the introduction of binary gratings, i.e., gratings that rely onlyon two refractive index values corresponding to the material beingetched or not etched, illuminated or not illuminated.

Two representations of multi-wavelength binary gratings are sampledgratings (SG) and superstructure gratings (SSG). The SG is constructedwith alternating sections of grating and grating-free regions of thewaveguide. The alternating sections produce diffraction spectraconsisting of multiple reflectance peaks contained within a (typically)symmetric envelope. The SG is intrinsically limited in the flexibilityin the location and relative strength of reflectance peaks, and, becauseof the large fraction of grating-free space, is also spatiallyinefficient. The SG is therefore particularly unsuitable where a shortgrating is required or where waveguide losses are high.

With the super-structure grating (SSG), the grating period is chirped byfinely varying the grating pitch, which corresponds to the length of onetooth-groove cycle. This can also be thought of as a sequence of finelytuned phase shifts; common phase profiles include linear and quadraticchirp. Such an implementation in principle allows arbitrary peakpositions and relative heights, but only at the expense of extremelyhigh resolution, corresponding to a very small fraction of the size ofthe grating teeth themselves.

Chirped Bragg Gratings are grating devices targeted at applications suchas dispersion compensation and optical pulse compression. Here a Bragggrating's pitch L is varied along its length. This produces awavelength-dependent phase spectrum which can be tailored to provide thedesired group delay spectrum: τ_(g)=−dφ/dω. The delay for a givenfree-space wavelength λ₀ then follows from the round-trip distance towhere local pitch has λ₀ as its Bragg wavelength:τ_(g)(λ₀)=2n_(eff)z(λ₀), where z(λ₀) is the spatial coordinate at whichΛ(z)=λ₀/2n_(eff). In practice, however, these implementations sufferfrom excessive group-delay ripple, indicating that the dispersioncompensation is not complete.

Dammann Gratings are binary gratings devices wherein the gratingfeatures are imposed on some surface and wherein the incident lightilluminates the surface at some normal or off-normal angle. The opticalwavefront incident on this grating experiences a one-time interactionwith the grating features and thereby experiences Raman-Nath typediffraction (as opposed to Bragg diffraction). This device is intendedfor free-space use and is not easily employed in guided-waveapplications. Furthermore, to achieve the wavelength resolutionrequirements imposed by modern optical communication systems theincident light must be collimated to a very high degree, which can provedifficult in practice.

Arrayed Waveguide Gratings (AWG) are used primarily to spatiallyseparate optical channels in a WDM environment. They operated bydividing input multi-wavelength light between an array of waveguides,wherein each waveguide is of a slightly different optical length. Theresulting optical phase differences between the waveguides' respectiveoutputs leads to a wavelength-dependent interference pattern, which withproper design can lead to a separation of wavelength components. Inpractice, this technology requires vast amounts of semiconductor realestate and imposes extreme manufacturing constraints.

Echelle gratings are also used primarily to spatially separate opticalchannels in a WDM environment. Here, a grating plane is generated bymeans of defining sub-wavelength reflective features at various glazingangles and potentially along some curved plane. The grating plane isthen illuminated with multi-wavelength light, often at an oblique angle,and the individual reflections add up to substantially separate thewavelength components. The device tends to be very difficult toimplement in practice, requiring both deep and flat etchingcharacteristics when implemented in semiconductor.

Prior art regarding binary superimposed grating synthesis is presentedin Ivan A. Avrutsky, Dave S. Ellis, Alex Tager, Hanan Anis, and J. M.Xu, “Design of widely tunable semiconductor lasers and the concept ofBinary Superimposed Gratings (BSG's),” IEEE J. Quantum Electron., vol.34, pp. 729-740, 1998.

Older methods in the prior art address the synthesis of “multi-peak”gratings—i.e., gratings characterized by reflectance at several “peaks”,which can be controlled in their position and strength. In thesemethods, a grating engineer begins with a set of sinusoids, eachsinusoid corresponding to a single reflectance peak and weightedaccording to that peak's desired relative strength. These peaks areadded together (i.e. superimposed; hence the BSG is known as asuperimposed grating) to produce an “analog profile”. This profile isthen digitally quantized by a simple threshold method. For example, ifthe analog profile value is positive (above a pre-selected reference)then the corresponding BSG segment is a high or binary 1 index value; ifit is negative, the corresponding BSG segment is a low or binary zeroindex value.

However, this approach is inadequate in at least two areas: firstly, thethreshold quantization process introduces intermodulation, which largelylimits the applicability of BSGs synthesized in this manner to activeapplications (laser feedback elements and the like). Secondly, thissynthesis procedure is limited to multi-peak gratings, and offers littleor no control over the individual peak shape. It is also entirelyincapable of generating flat-top channels, as desired by somecommunication applications, and of generating the near-arbitraryreflectance spectra demanded by some gain- and dispersion-compensationschemes.

Other methods for BSG synthesis include trial-and-error methods that aremost often computationally difficult and inefficient.

Therefore, for detecting optical wavelengths in optical devices it isdesirable to provide methods and apparatuses for overcoming thedisadvantages noted above.

SUMMARY OF THE INVENTION

In accordance with one embodiment of the present invention an opticalcomponent including at least one optical supergrating is provided. Theat least one optical supergrating includes a quantized refractive indexprofile adapted to exhibit a finite plurality of refractive indexes;which in turn are adapted to generate a reflectance spectrum in at leastone spectral band.

In accordance with another embodiment of the present invention a methodof transmitting at least one optical signal from a first point to asecond point is provided. The method includes providing at least onefirst optical waveguide including an optical component. The opticalcomponent includes at least one optical supergrating, having a quantizedrefractive index profile adapted to exhibit a finite plurality ofrefractive indexes. The finite plurality of refractive indexes areadapted to generate a reflectance spectrum in at least one spectral bandcorresponding to a Fourier transformed analog refractive index profile.The method includes transmitting the at least one optical signal throughthe at least one first optical waveguide; and receiving the at least oneoptical signal at the second point.

In accordance with another embodiment of the invention an opticalcomponent including at least one optical supergrating is provided,wherein the at least one optical supergrating comprises a binaryquantized refractive index profile adapted to exhibit a finite pluralityof refractive indexes. The indexes are adapted to generate a reflectancespectrum in at least one spectral band.

In accordance with another embodiment of the present invention a methodof processing at least one optical signal is provided. The methodincludes providing at least one optical component having at least oneoptical supergrating. The at least one optical supergrating includes aquantized refractive index profile adapted to exhibit a finite pluralityof refractive indexes adapted to generate optical characteristics in atleast one spectral band. The method also includes adapting the at leastone optical component to affect the at least one optical signal.

In accordance with another embodiment the invention is also directedtowards an optical component including at least one opticalsupergrating. The at least one optical supergrating includes a binaryquantized refractive index profile adapted to exhibit a finite pluralityof refractive indexes adapted to generate a reflectance spectrum in atleast one spectral band.

The invention is also directed towards a method of monitoring thestability of an optical system. The method includes providing at leastone optical component having at least one optical supergrating having aquantized refractive index profile. The quantized refractive indexprofile is adapted to exhibit a finite plurality of refractive indexesadapted to generate optical characteristics in at least one spectralband. The method also includes providing a plurality of opticaldetectors; providing processing electronics; and adapting the at leastone optical component to affect at least one chosen wavelength componentto interact with the plurality of optical detectors.

In accordance with another embodiment of the invention, a programmableoptical component is provided. The programmable optical componentincludes at least one optical supergrating having a quantized refractiveindex profile adapted to exhibit a finite plurality of refractiveindexes adapted to generate spectral characteristics in at least onespectral band.

In accordance with another embodiment of the invention an opticalcomponent is provided. The optical component includes at least onescattering-reducing optical supergrating having a quantized refractiveindex profile adapted to exhibit a finite plurality of refractiveindexes adapted to generate spectral characteristics in at least onespectral band. The supergrating also has at least one grating featuredimension exceeding grating material wavelength λ_(mat)=λ₀/n_(eff), anda decay constant of the modal tail less than 1/λ_(mat) in apredetermined region of the at least one scattering reducing opticalsupergrating.

In accordance with another embodiment of the invention an opticalcomponent is provided. The optical component includes at least onemulti-dimensional optical supergrating having a quantized refractiveindex profile. The quantized refractive index profile is adapted toexhibit a finite plurality of refractive indexes adapted to generatespectral characteristics in at least one spectral band.

The invention is also directed towards an optical coupler system forcoupling light between waveguides. The optical coupler includes at leastone first optical waveguide and at least one second optical waveguide.The optical coupler also includes at least one optical componentoptically coupling the light from the at least one first opticalwaveguide to the at least one second optical waveguide. The at least oneoptical component includes a quantized refractive index profile, whereinthe quantized refractive index profile is adapted to exhibit a finiteplurality of refractive indexes adapted to generate spectralcharacteristics in at least one spectral band.

In accordance with another embodiment of the invention an optical deviceis provided. The optical device includes at least one optical waveguidehaving an optical component for reflecting light within the at least oneoptical waveguide. The optical component includes a quantized refractiveindex profile adapted to exhibit a finite plurality of refractiveindexes adapted to generate spectral characteristics in at least onespectral band. In addition, the optical component includes an opticalcirculator having at least one optical port, and optically coupled tothe at least one optical waveguide and adapted to direct the reflectedlight to the at least one optical port.

In accordance with another embodiment of the invention an opticaldispersion control system is provided. The system includes at least onefirst optical waveguide adapted to exhibit wavelength-dependent opticalphase characteristics. The at least one optical waveguide includes atleast one optical component having a quantized refractive index profileadapted to exhibit a finite plurality of refractive indexes adapted togenerate spectral characteristics in at least one spectral band.

In accordance with another embodiment of the invention an opticaldispersion control system is provided. The system includes an opticalcoupler system for coupling light between waveguides and adapted toexhibit wavelength-dependent optical phase characteristics. The opticalcoupler system includes at least one first optical waveguide and atleast one second optical waveguide. The system also includes at leastone optical component optically coupling the light from the at least onefirst optical waveguide to the at least one second optical waveguide.The at least one optical component includes a quantized refractive indexprofile adapted to exhibit a finite plurality of refractive indexesadapted to generate spectral characteristics in at least one spectralband.

In accordance with one embodiment of the invention an optical device forseparating wavelength components of an optical signal is provided. Theoptical device includes at least one optical wavelength separationsystem having at least one first optical waveguide and at least onesecond optical waveguide. The optical device also includes at least oneoptical component optically coupling the at least one optical wavelengthfrom the at least one first optical waveguide to the at least one secondoptical waveguide. The at least one optical component includes aquantized refractive index profile adapted to exhibit a finite pluralityof refractive indexes adapted to generate spectral characteristics in atleast one spectral band.

The invention is also directed towards a wavelength stability monitor.The wavelength stability monitor includes a wavelength monitor having atleast one optical component. The monitor also includes a quantizedrefractive index profile adapted to exhibit a finite plurality ofrefractive indexes adapted to generate spectral characteristics in atleast one spectral band. The monitor also includes a plurality ofoptical detectors coupled to the wavelength monitor which are adapted togenerate a deviation signal when a monitored wavelength deviates. Inaddition a controller coupled to the plurality of optical detectors isadapted to generate an electrical signal corresponding to wavelengthdeviation.

The invention is also directed towards an optical wavelength equalizerincluding at least one optical component. The at least one opticalcomponent includes a quantized refractive index profile adapted toexhibit a finite plurality of refractive indexes adapted to generatespectral characteristics in at least one spectral band. The opticalcomponent is also adapted to adjust wavelength power per wavelength inan optical signal.

In accordance with another embodiment of the invention an opticalwavelength monitor is provided. The optical wavelength monitor includesat least one optical component, having a quantized refractive indexprofile adapted to exhibit a finite plurality of refractive indexesadapted to generate spectral characteristics in at least one spectralband. The at least one optical component is adapted to measure power perwavelength in an optical signal.

In accordance with another embodiment of the invention an opticalcomponent is provided. The optical component includes at least oneprogrammable optical supergrating.

The invention is also directed towards an optical component comprisingat least one tuneable optical supergrating. The tuneable opticalsupergrating includes a quantized refractive index profile adapted toexhibit a finite plurality of refractive indexes adapted to generatespectral characteristics in at least one spectral band.

The invention is also directed towards an optical component having atleast one optical supergrating adapted to effect optical phasecharacteristics in at least one spectral band.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing aspects and other features of the present invention areexplained in the following description, taken in connection with theaccompanying drawings, wherein:

FIG. 1 is a flow chart showing method steps of one method forsynthesizing a BSG incorporated by the invention embodiments presentedherein;

FIG. 2 shows a pictorial view of a counter directional couplerincorporating features of the present invention;

FIG. 3 shows a pictorial view of a co-directional coupler incorporatingfeatures of the present invention;

FIG. 3A shows a pictorial view of a counter-directional symmetricalwaveguide coupler incorporating features of the present invention;

FIG. 4 shows a pictorial view of a dispersion compensator incorporatingfeatures of the present invention;

FIG. 4A shows a pictorial view of a dynamic add/drop filter embodimentincorporating features of the present invention;

FIG. 4B shows a pictorial view of multiple waveguides coupled withprogrammable BSGs incorporating features of the present invention;

FIG. 5 shows a pictorial view of an alternate embodiment of a dispersioncompensator incorporating features of the present invention;

FIG. 6 shows a pictorial view of a wavelength monitor incorporatingfeatures of the present invention;

FIG. 7 shows a pictorial view of a wavelength monitor incorporatingfeatures of the 2D embodiment of the present invention;

FIG. 8 shows a pictorial view of a wavelength monitor incorporatingfeatures of the point scatterer array embodiment of the presentinvention;

FIG. 9 is a diagram of a Lambda router incorporating features of thepresent invention; and

FIG. 10 is a pictorial diagram of an intra-waveguide suppression couplerincorporating features of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Although the present invention will be described with reference to thesupergrating embodiments as shown in the drawings, it should beunderstood that the present invention can be embodied in many alternateforms of embodiments, and it is not intended that this invention islimited only to that particular type of embodiment. In alternateembodiments the present invention could be used in any suitable opticaldevice requiring one or more optical gratings.

Starting with supergratings as used here, it will be appreciated thatthere are three main properties that differentiate the supergrating fromother grating technologies. The first is that the supergrating relies ona discrete number of effective refractive index levels. This number ishistorically 2 and hence the supergrating can take the form of a binarygrating, in which case it is known as the Binary Supergrating (BSG). Forthe sake of clarity and illustration this description will focus on thebinary embodiment of the present invention, however, it will beappreciated that in alternate embodiments any suitable number ofdiscrete levels of effective refractive index may be used. The differentvalues of effective refractive index may be attained by varying the realrefractive index in any part or in the neighborhood of the supergrating,or by any other method that varies the effective refractive indexexperienced by propagating light, and it will be appreciated that manyembodiments are possible within the present invention.

The second defining property of the supergrating is that the gratingresembles a sampled structure characterized by a set of sample points,each associated with a sample region. These sample regions, which maytake a variety of shapes, are often referred to as refractive indexpixels. The supergratings effective refractive index is substantiallyfixed within each pixel. This refers to the fact that transitionsbetween the grating's index levels cannot occur at arbitrary positions,but, rather, must occur at boundaries of regions defined by the samplepoints. Thus, the BSG can be described by a series of (often binary)digits, indicating the refractive index setting at each sample point(see FIG. 5).

The third defining property of the supergrating is that an opticalwave-front incident on the grating experiences multiple interactionswith the grating features. That is, the supergrating operates in theBragg diffraction regime.

Certain supergrating embodiments utilize a sequential array ofrefractive index pixels, meaning that each pixel is neighbored by onlytwo other pixels, leading to a natural sense of ordering. Suchembodiments are referred to as one-dimensional supergratings, and oftenutilize pixels in the shape of straight or curved lines, or arrays ofboxes or dots arranged along the direction of propagation of incidentlight. It should be noted that these embodiments include the suitablevariation of effective refractive index along the length of anywaveguide confining propagation along one dimension.

Other supergrating embodiments utilize two-dimensional arrays ofrefractive index pixels wherein the pixels are situated on the sametwo-dimensional surface. This surface can be planar or curved. Suchembodiments often make use of square or hexagonal pixels that arearranged along a suitable periodic lattice, although it may beappreciated that non-periodic arrangements, non-uniform pixels, or otherpixel shapes may be suitable and are within the context of the presentinvention. It should be noted that these embodiments include thesuitable variation of effective refractive index in the span of anywaveguide confining propagation along two dimensions.

Additional supergrating embodiments utilize three-dimensional arrays ofrefractive index pixels. Here, the sample points may be situatedanywhere or confined to any particular region of space. Such embodimentsoften make use of box-like or diamond-like pixels that are arrangedalong a suitable periodic lattice, although it may be appreciated thatnon-periodic arrangements, non-uniform pixels, or other pixel shapes maybe suitable and are within the context of the present invention.

Referring now to FIG. 1, supergrating construction involves several keychoices. First, Step 351 Selects the refractive index levels for theoptical device, as determined from material parameters and lithographicor photoinscription constraints. Step 352 then determines the desiredsample length, considering the desired wavelength range for the gratingand the available lithographic resolution. Step 353 sets total devicedimensions for the grating, limited by the available physical space andthe technological limitations of the inscribing process. It will beappreciated that the methods described herein are for determininggrating patterns for surface-relief gratings; however, in alternateembodiments the methods may be readily adapted to fiber gratingpatterns. The next step 354 converts the desired grating's reflectancespecifications to the Fourier domain using the Fourier approximation.Guided by the Fourier approximation, the designer may initially designthe grating by its Fourier spectrum. As will be shown below, this stepcan also implement feedback to account for various inaccuracies of theapproximation in order to improve the final result.

Step 353, the Fourier approximation, is a mathematical relation thatrelates a grating's reflectance spectrum to one or more periodicreflectance spectra. In other words, single-wavelength gratings havereflectance spectra characterized precisely by their periodic structure,and simple superimposed gratings have reflectance spectra characterizedby their wavelength or reflectance spectra components. Therefore, thereflectance spectrum of a grating may be related to the Fouriertransform of its structure—the Fourier transform being the standardmethod for evaluating the “frequency content” or “wavelength content” ofa waveform.

The next step 355 is quantization of the analog index profile.Delta-Sigma modulation is one such quantization technique that may beused and can be efficiently implemented. It will be appreciated that inalternate embodiments any suitable quantization technique that conservesFourier information within a spectral band may be used.

Step 356 determines the supergrating's actual reflectance using an exacttechnique such as the known transfer matrix method. This calculationdetermines residual errors of the Fourier approximation, and quantifiesan error that can be taken back into the Fourier domain and added to theresult of the step 353 if step 357 determines that the error exceeds apredetermined threshold. This process can be repeated as necessary,although one repetition is often sufficient. It will be appreciated thatany suitable technique for determining error between the desiredreflectance characteristics and actual reflectance characteristics maybe used.

In accordance with one aspect of the invention, deeper, or moreprofound, supergrating surface features reduce scattering losses due toradiative cladding modes by occupying a greater distance in the normaldirection, which, from Huygens principle and Fourier considerations,leads to more robust phase-matching requirement in the normal dimension;thereby reducing (unwanted) scattering efficiency. More quantitatively,grating features are preferably deep-toothed to a depth exceeding thematerial wavelength λ_(mat)=λ₀/n_(eff), and the decay constant of themodal tail is preferably less than 1/λ_(mat) in the grating region. Inalternate embodiments of the invention, the BSG can be implemented inthe core region at the mode's center. Thus, contributions from thenormal extent of the grating are relatively equal, thereby enhancingcancellation of the scattered component.

In accordance with another aspect of the invention, grating features andoptical characteristics may be varied one or more times aftermanufacture by employing any means of modifying material or effectiverefractive index locally or over an area. Several such methods ofmodifying material or effective refractive index include: affecting thetemperature of any part or the neighborhood of the supergrating;electro-optic, magneto-optic, electro-strictive, or magneto-strictivetuning of any part or the neighborhood of the supergrating; opticallyilluminating, mechanically straining, or injecting current into any partor the neighborhood of the supergrating; incorporating an electrochromicmaterial in any part or the neighborhood of the supergrating;incorporating a liquid crystal or optical polymer material in any partor the neighborhood of the supergrating; promoting chemical reaction orreconfiguration in any part or the neighborhood of the supergrating; oreffecting a mechanical translation or reconfiguration of any part or theneighborhood of the supergrating. It will be appreciated that othermethods for modifying material or effective refractive index, any one orcombination of which are within the context of the present invention.

Some embodiments apply one or more methods of modifying material oreffective refractive index to the entire supergrating or substantialparts or sections thereof, thereby effecting a general change in thesupergrating's optical features. Such general changes include thestrengthening or weakening of features, the enablement or disablement ofsupergrating features of the supergrating as a whole, the tuning of theoptical phase of supergrating features, or the spectral shift ofsupergrating features. These embodiments address what we term a “tunablesupergrating”. These tunable supergratings may be used interchangeablywith other supergratings to provide additional dynamic functionality inany device or embodiment where the latter are used. This is true inparticular for all other device embodiments of the present invention.

Other embodiments apply one or more methods of modifying material oreffective refractive index to individual pixels of the supergrating orgroups thereof. Such embodiments may achieve spectral changes includingthe strengthening or weakening of features, the enablement ordisablement of supergrating features of the supergrating as a whole, thetuning of the optical phase of the supergrating features, or thespectral shift of supergrating features, generally in greater extentthan is possible with tunable supergratings. Furthermore, suchembodiments may act to create spectral features that were previously notexhibited by the supergrating, remove spectral features that werepreviously exhibited, or even change the optical characteristicsexhibited by the supergrating within a spectral band entirely. Theseembodiments address what we term a “programmable supergrating”. Theseprogrammable supergratings may be used interchangeably with othersupergratings to provide additional dynamic or programmablefunctionality in any device or embodiment where the latter are used.This is true in particular for all other device embodiments of thepresent invention. Particularly, embodiments of optical couplers,optical dispersion controllers, optical spatial separators, add/dropfilters, lambda routers and wavelength equalizers wherein a programmablesupergrating is used are possible, and represent much improvedfunctionality.

Supergrating Coupler

Features of the present invention may be used in evanescent-wavecouplers to provide wavelength dependent coupling and direction as wellas dispersion compensation. For example, light may be coupled from onewaveguide to another waveguide, with a desired spectral response: i.e.,light at a given wavelength may be coupled fully, fractionally, or notat all, and with a desired phase.

The coupling embodiments may consist of two or more parallel asymmetricor symmetric waveguides (described below). The asymmetric waveguideshave overlapping but differing modes, with differing effective (modal)indices (n_(eff))₁ and (n_(eff))₂ and different propagation vectorsk₁(λ₀)=2π(n_(eff))1/λ₀ and k₂(λ₀)=2π(n_(eff))2/λ₀, where λ₀ isfree-space wavelength. The effective indices will in general bedependent on wavelength λ₀. It will be appreciated that the amount ofmodal overlap and the characteristics of the supergrating will determinethe wavelength(s) coupled from one waveguide to another and thedirection the wavelength(s) will take once coupled.

Optical coupling may be classified into two general categories:counter-directional and co-directional. Light is said to be coupledco-directionally if the coupled light travels in the same generaldirection (within 90 degrees of) the input light. Light is said to becounter-directionally coupled if the coupled light travels generally inthe opposite direction of the input light. These distinctions are mostoften very clear in practice as the counter- and co-directions are welldefined by the optical waveguides. It should be noted that the samesupergrating coupler may be used to couple both co- andcounter-directionally, and may do either or both for each wavelengthwithin one or more spectral bands. It is appreciated that while deviceoperation is simpler to describe if only one mode of operation isconsidered, a device incorporating features of both embodimentssimultaneously is within the present invention. It is also appreciatedthat in accordance with several embodiments of the present invention,the coupling characteristics of supergrating couplers may be variedafter manufacture, most often by subjecting the supergrating orsupergratings responsible for coupling to some form of optical tuningsuch as those mentioned previously. Any form of supergrating, includingone-dimensional, two-dimensional or three-dimensional, and anyparticular method of effecting the required effective refractive indexvalues is within the context of the present invention.

Counter-directional Supergrating coupler Embodiments

Referring now to FIG. 2 there is shown a pictorial illustration of acounter-directional supergrating coupler 154 incorporating features ofthe present invention. For this embodiment, counter-directional couplingwill occur for a given input wavelength λ₀ when the index perturbationcomprises a spatial frequency of K_(g)(λ₀)=k₁(λ₀)+k₂(λ₀). Again, this isaccomplished by a constructing the supergrating 152, as described above,to emulate the desired spectrum of K_(g)(λ₀) and situating thesupergrating 152 between the evanescent-coupled waveguides 151,153. Inthis embodiment, the supergrating 152 should preferably be free ofspatial frequencies of 2k₁(λ₀) and 2k₂(λ₀), as these will produceback-reflection within the respective waveguides (i.e. no coupling),thereby decreasing coupling efficiency and yielding undesiredback-reflection. Satisfying this condition requires that waveguideasymmetry be sufficient to avoid any overlaps between grating spatialfrequencies (K_(g)'s) yielding inter-waveguide coupling and thoseyielding intra-waveguide coupling, over all wavelength range(s) ofinterest; mathematically, this can be expressed as:k ₁(λ₁)+k ₂(λ₁)≠2k ₁(λ₂) and k ₁(λ₁)+k ₂(λ₁)≠2k ₂(λ₂)

where k₁ and k₂ are defined earlier with wavelength-dependent effectiveindexes, and λ₁ and λ₂ are any combination of wavelengths lying withinthe range(s) of interest.

In alternate embodiments, optical BSG 152 characteristics may beprogrammable and/or tuneable by controller 152A and/or tuner 152B,respectively.

Co-directional Supergrating Coupler Embodiment

Referring to FIG. 3 there is shown a pictorial illustration of aco-directional supergrating coupler 164 incorporating features of thepresent invention. In this embodiment, a desired wavelength λ willcouple co-directionally from one waveguide 161 to the other 163, whenthe respective effective indexes are perturbed with spatial frequencyK_(g)(λ₀)=k₁(λ₀)−k₂(λ₀). This is accomplished by a constructing thesupergrating 162, as described above, to emulate the desired spectrum ofK_(g)(λ₀) and situating the supergrating between the evanescent-coupledwaveguides 161,163.

In alternate embodiments the supergrating is part of the waveguide or onone or more sides of the waveguide. In addition, alternate embodimentsoptical BSG 162 characteristics may be changed by programmablecontroller 162A and/or tuner 162B, respectively.

Symmetric Supergrating Coupler Embodiment

Referring to FIG. 3A, it will be appreciated that the symmetricsupergrating coupler 164A is a special case of the asymmetricsupergrating coupler shown in FIG. 2, and performs similar functions asthe asymmetric coupler 154 but allows the two waveguides 161A, 163A tobe weakly asymmetric or even symmetric in their effective index. Thus,limitations expressed previously may be exceeded, independent of thefact that this would normally lead to intra-waveguide reflection.

In alternate embodiments the supergrating is part of the waveguide or onone or more sides of the waveguide. In addition, alternate embodimentsmay also change optical BSG 162 characteristics through programmablecontroller 162A and/or tuner 162B, respectively.

Referring to FIG. 10 there is shown a pictorial diagram of anintra-waveguide suppression coupler incorporating features of theinvention. For example, a device 106 consisting of two waveguides 101,102 (symmetric or otherwise) with a BSG 104 situated in between may bestatic, tunable, or programmable as necessary. Two more BSGs, 103,105identical to the first BSG 104, but with opposite contrast (1's become0's and vice-versa), are placed on either side of the two waveguides101,102 such that they mirror the center BSG 104 about the correspondingwaveguide.

The principle of operation is as follows: let m₁ be the modal profile ofguide 1 and m₂ be the modal profile of guide 2. The couplingcoefficients relating the two waveguides can be written to first orderin grating strength as:C ₁₂ ∝∫m ₁ *m ₂ G ₁₂ +∫m ₁ m ₂(G ₁₁ +G ₂₂)≈∫m ₁ *m ₂ G ₁₂,

where G₁₂ is the center grating 104 and G₁₁ 103 & G₂₂ 105 are thegratings on the far side of waveguides 1 and 2, respectively. The secondterm is negligible because the two side gratings 103, 105 are very farfrom the corresponding opposite waveguide (more precisely, the oppositewaveguide's modal profile is negligible in this region).

However, the coupling coefficient from the first waveguide 101 to itself(corresponding to intra-waveguide reflection) follows:C ₁₁ ∝∫|m ₁|² G ₁₁ +∫|m ₁|² G ₁₂=0 (because G₁₁=−G₂₂ and symmetry)

The result is identical for the second waveguide 102. The onlyassumption necessary for the cancellation is that the modal profiles ofboth waveguides 101,102 be symmetric (about their waveguide, notnecessarily identical to each other) and that the gratings be properlysymmetrized about the guide. The cancellation is independent of manymaterial parameters such as the waveguides' effective indices, even ifthey vary independently.

It will be appreciated that the invention advantageously allows forefficient coupling between neighboring symmetric waveguides, whilesuppressing intra-waveguide reflection.

It will be further appreciated that the invention advantageously allowsfor efficient coupling between neighboring symmetric waveguides, whilesuppressing intra-waveguide reflection. It is appreciated that theinvention is equally applicable to asymmetric waveguides, and inalternate embodiments may be the preferred embodiment in light of itsrelaxation of the design requirements.

Coupler Folding

In another embodiment of the present invention, one supergrating couplermay be folded to make better use of chip real estate. This is done bycascading supergrating couplers. The exact choice of connection order ordirection depends on the directionality of coupling of the wavelengthsof interest, and a combination of operating modes may be used at onetime. The several supergrating couplers may be used together to form oneor more improved couplers, or to subject input light to several stagesof filtering of processing.

FIG. 4 represents a cascaded counter-directional coupler 176 embodiment.In this embodiment wavelength I1 is counter-directionally coupled fromwaveguide 171 to waveguide 173, and again counter directionally coupledfrom waveguide 173 to waveguide 175. It will be appreciated thatwaveguide 173 may be adapted to compensate for dispersion in waveguide171.

In alternate embodiments optical BSG 172 characteristics may beprogrammed and/or tuned through programmable controller 172A and/ortuner 172B, respectively. Likewise, optical BSG 174 characteristics maybe programmed and/or tuned through programmable controller 174A and/ortuner 174B, respectively.

Optical Circulator-based Couplers

FIG. 5 illustrates another embodiment of the present invention wherein asupergrating optical coupling between two or more waveguides is achievedby means of a supergrating operating in a reflective mode. Lightincident through an input waveguide enters an optical circulator throughport 1 and is transmitted through to port to. At port 2, the light isincident on a supergrating and selectively reflected in amplitude andphase and as a function of wavelength back to port two. The opticalcirculator acts to direct the light returning to port 2 to port 3,wherein it is collected by an output waveguide. The circulator basedembodiment has the advantage that it is very suitable to situationswhere the waveguides are optical fibers as fiber based circulators arereadily available.

optical BSG 184 characteristics may be programmed and/or tuned throughprogrammable controller 184A and/or tuner 184B, respectively.

Dispersion Compensator Embodiment

In the field of optical transmission, it is well known that opticalnetworks must contend with a property known as dispersion. This propertyarises from the wavelength-dependence of effective index, which in turnproduces a wavelength-dependent group delay spectrum for a given typeand length of optical fiber. Since an optical pulse always possessessome spectral width, this wavelength-dependence leads to differentretardation of various spectral components of the optical pulse, therebyleading to its spread in the spatial domain. This spread directlyimpedes the operation of the optical network.

Chirped Bragg Gratings are grating devices targeted at dispersioncompensation. Here a Bragg grating's pitch A is varied along its length.This produces a wavelength-dependent phase spectrum which can betailored to provide the desired group delay spectrum: τ_(g)=−dφ/dω. Thedelay for a given free-space wavelength λ₀ then follows from theround-trip distance to where local pitch has λ₀ as its Bragg wavelength:τ_(g)(λ₀)=2n_(eff)z(λ₀), where z(λ₀) is the spatial coordinate at whichΛ(z)=λ₀/2n_(eff). In practice, however, these implementations sufferfrom excessive group-delay ripple, indicating that the dispersioncompensation is not complete.

In the present invention a supergrating emulating the effect of achirped Bragg grating may be implemented by determining the ideal(analog) input chirp function, as derived from the group delay spectrumτ_(g)(λ₀) (grating-imposed delay is preferably the opposite of that atthe input). The ideal analog profile is then fed into the previouslydescribed supergrating quantization filter, producing a quantizedprofile that emulates the desired phase characteristics. Thequantization filter may be further optimized as described above tominimize phase noise.

In other embodiments of the present invention the supergrating may besynthesized directly from the required phase-delay characteristics, forinstance by Fourier-based synthesis of the specifications.

Different embodiments of the present invention may comprise supergratingcouplers, as described above. These couplers may include co-directionaland counter-directional couplers, optical circulator based couplers,folded couplers, or any combination of these, but not limited to these.It is appreciated that any optical transmission or direction methodwherein a one or more supergratings affect the transmitted or directedlight may support the desired optical phase characteristics and is hencewithin the context of the present invention.

Alternate embodiments of the present invention may involve one or moresupergratings adapted to influence light as it is transmitted throughthe length of a waveguide. These transmission-based embodiments areparticularly useful for optical fiber implementations.

Wavelength Stability Monitor Embodiments

To function properly, optical networks require that channel wavelengthsremain within some range of their nominal value. Drifting can be causedby a number of factors, including variations in environmentalconditions, device aging, and mechanical disruptions. In certainsituations, the incident wavelength channel may remain within the rangeof nominal values but the characteristics of a device processing thiswavelength channel may shift relative to it. A supergrating device maybe used to track such deviations and provide feedback to this device, orto a subsequent device attempting to correct the problem.

Wavelength drift can be monitored using a 1D supergrating 192 as shownin FIG. 6. While light incident at a given input angle on tilted 1Dgrating 192 will nominally diffract at only a particular output angle,detuning from a central peak-reflectance wavelength will in fact yield adetuning in angle, along with a decrease in diffraction efficiency.

This behavior can be used to detect shifts in wavelength, or, assumingthe wavelength to be true, shifts in device characteristics which canthen be compensated through a variety of mechanisms (e.g. temperaturetuning). This may be accomplished by placing photodetectors 193 a, 193 bsymmetrically aligned along the diffraction path of the desired centralwavelength; in this configuration, the signal from each will match iflocal wavelength matches the desired value. (Note that diffractionefficiency will normally be intentionally low, so that most power passesthrough un-deviated.) Deviations in local wavelength are then manifestby a change in the relative values of the photodetectors 193 a, 193 b,which is monitored by comparator 194. Comparator 194 may determine adifference between the input signals on paths 196, 197, or any suitablesensitivity function may be used, such as a logarithmic subtraction.These deviations can then be corrected for using temperature or anyother influencing parameter (not shown).

In alternate embodiments optical BSG 192 characteristics may beprogrammed and/or tuned through programmable controller 192 c and/ortuner 192 d, respectively.

Another embodiment of the present invention uses a 2D BSG 201 as shownin FIG. 7, which may be used to diffract light to the detectors and/ordetect drifts in wavelength on several channels simultaneously; or inanother embodiment, with a sequence of quasi-1D (i.e. point-source)features 201 etched along a waveguide as shown in FIG. 8, which willlead to symmetric diffraction in both lateral directions. A mirror 202can optionally be etched at one side, for optimal collection ofscattered light.

Dynamic multi-wavelength equalizer

According to several embodiments of the present invention dynamicequalization of multi-wavelength light may be effected. Theseembodiments comprise one or more supergratings to attainwavelength-specific optical gain or loss characteristics, and therebyeffect equalization. The dynamic behavior may be attained by utilizingone or more programmable or tunable supergratings.

A dynamic multi-wavelength equalizer according to the present inventionmay be preceded by first routing input wavelengths through a tap-offnetwork monitor that separates channels and monitors their power (seeFIGS. 6 and 7). These signals are sent through processing electronics194, whose output tunes (or programs) the one or more supergratings ofthe multi-wavelength equalizer 192B, which equalize the power acrosschannels 191,191A. Such a configuration may be used as part of afeedback configuration to balance wavelength power.

According to some embodiments of the present invention one or moresupergratings are used to couple input channels to an output waveguidewith lower efficiency for wavelengths whose power must be trimmed. Theseembodiments may comprise one or more supergrating couplers. Otherembodiments of the present invention include using supergrating toimpose higher scattering losses for wavelengths whose power must betrimmed.

In alternate embodiments a cascade of BSGs that include “basisfunctions” can be independently tuned to effect the loss spectrumrequired for equalization; possible basis functions include step-likespectra that can be shifted relative to one another.

Further alternate embodiments include using a programmable supergratingdevice whose refractive index features are modified to effect thedesired equalization.

Particular embodiments include: a cascade of co- and counter-directionalBSGs (see FIGS. 2, 3, 3A, and 4), which successively divide the channelsin two sub-bands until individual channels are extracted; and a sequenceof tilted single-channel gratings which direct individual channels totheir respective output waveguide or detector device (FIG. 6, item 193).

Static and Dynamic Add/Drop Filter Embodiment

According to several embodiments of the present invention individual ormultiple wavelength channels may be fully or partially spatiallyseparated from an “in” channel and directed to a “drop” channel. Otherwavelength channels may be directed from the “in” channel to an “out”channel. Optionally, an “add” channel may be provided, wherein lightfrom the “add” channel may be selectively directed to the “through”channel. Other embodiments may comprise several “drop”, “add” or“through” channels. The device functionality in both types ofembodiments may be fixed or programmable.

Referring to FIG. 4A, there is shown a device 4A1 consisting of a set ofwaveguides 4A3, 4A4 coupled using tunable and/or programmable or fixedcounter- and/or co-directional supergrating couplers.

Another embodiment FIG. 4B makes use of the Vernier tuning principle,with a design motivated by the principle that the spectral shiftsaccessible through index tuning are often much less than the totaldesired tuning range. Multi-channel input enters along one waveguide4B3, with light coupled to an adjacent waveguide by a multi-peak tunablesupergrating 4B2 (with peak spacing generally less than the availabletuning range). A subsequent tunable supergrating 4B6 (generallymulti-peak with a different spacing which is also less than theavailable tuning range) couples a subset of this first set of channelsto a third waveguide 4B7. This decimation process can continue asdesired, with the supergratings independently tuned relative to oneanother to drop desired channel(s). The channel selection range can thusgreatly exceed the available index-tuned spectral shift.

Other embodiments of the present invention include using atwo-dimensional or three-dimensional supergrating to direct light intothe appropriate channel.

A particular embodiment of the invention can be used to spatiallyseparate all of the wavelength components of an input optical signal.

Lambda Router Embodiment

A Lambda router incorporating features of the present invention is shownin FIG. 9. Lambda routers are also known as called wavelength routers,or optical cross-connects (OxCs)—and are devices positioned at networkjunction points which route wavelength(s) from a specific fiber opticinput to another specific fiber optic output. Lambda routers aregenerally N×N devices (i.e. with N input fibers I and N output fibersO), with each input fiber typically conveying a single wavelengthchannel.

Cross/bar operation (i.e. channel light on one waveguide will couple tothe other, and vice versa; or will remain on the same waveguide) isachieved by locally tuning and/or programming the supergratings221A-221F in or out of alignment with the channel wavelength.

Another embodiment of the present invention comprises one or moresupergrating couplers to effect the desired routing. Other embodimentscomprise one or more add/drop filters.

Wavelength Monitor

According to another embodiment of the present invention, a supergratingdevice may measure the power in one or more optical wavelength channels.Several embodiments of this device comprise one or more supergratingsand one or more optical detectors. Alternative embodiments include oneor more supergrating couplers or one or more two- or three-dimensionalsupergratings.

It should be understood that the foregoing description is onlyillustrative of the invention. Various alternatives and modificationscan be devised by those skilled in the art without departing from theinvention. Accordingly, the present invention is intended to embrace allsuch alternatives, modifications and variances that fall within thescope of the appended claims.

1. An optical component comprising at least one optical supergrating,wherein the at least one optical supergrating comprises a quantizedrefractive index profile, wherein the quantized refractive index profileis adapted to exhibit a finite plurality of refractive indexes adaptedto generate optical characteristics in at least one spectral band. 2.-4.(canceled)
 5. An optical dispersion controller comprising: a firstoptical component, wherein the first optical component comprises theoptical component as in claim 1, wherein the first optical component isadapted to affect a first chosen wavelength; a first optical waveguide;and a second optical waveguide, wherein the second optical waveguide isasymmetric with the first optical waveguide, wherein the first opticalwaveguide is optically coupled to the second optical waveguide via thefirst optical component.
 6. An optical dispersion controller comprising:a first optical waveguide; a second optical waveguide, the secondoptical waveguide comprising: an optical component as in claim 1,wherein the optical component is adapted to reflect at least one chosenoptical wavelength; a third optical waveguide; and an opticalcirculator, wherein the optical circulator optically couples the first,second, and third optical waveguides.
 7. An optical wavelength stabilitymonitor system comprising: a first optical waveguide comprising: anoptical component as in claim 1, wherein the optical component isadapted to affect at least one chosen optical wavelength; a plurality ofoptical detectors, the plurality of optical detectors adapted to receivethe affected chosen optical wavelength and generate a plurality ofelectric signals; and an electronic processor electrically coupled tothe plurality of optical detectors, wherein the electronic processor isadapted to produce an electric signal from the plurality of electricsignals.
 8. An optical wavelength monitor system as in claim 7 furthercomprising an optical reflector.
 9. A symmetric optical couplercomprising: the optical component as in claim 1, wherein the opticalcomponent is adapted to affect at least one chosen optical wavelength; afirst optical waveguide; and a second optical waveguide, wherein thesecond optical waveguide is symmetric with the first optical waveguide,wherein the second optical waveguide is optically coupled to the firstoptical waveguide via the optical component.
 10. An optical couplercomprising: a plurality of optical components as in claim 1, wherein theplurality of optical components is adapted to affect at least one chosenoptical wavelength; a first optical waveguide; and a second opticalwaveguide, wherein the second optical waveguide is optically coupled tothe first optical waveguide via the plurality of optical components,wherein the plurality of optical components are adapted to effect adesired inter-waveguide and intra-waveguide coupling.
 11. A method ofdirecting at least one optical signal from a first point to a secondpoint, the method comprising providing an optical component, wherein theoptical component comprises at least one optical supergrating, whereinthe at least one optical supergrating comprises a quantized refractiveindex profile, wherein the quantized refractive index profile is adaptedto exhibit a finite plurality of refractive indexes adapted to generateoptical characteristics in at least one spectral band, and wherein theat least one optical supergrating is adapted to influence the at leastone optical signal.
 12. A method as in claim 11 further comprising:providing at least one first optical waveguide; providing at least onesecond optical waveguide; adapting the optical component to affect atleast one chosen wavelength; and optically coupling the at least onechosen wavelength from the at least first optical waveguide to the atleast one second optical waveguide via the optical component.
 13. Amethod as in claim 12 wherein providing the at least one first opticalwaveguide and the at least one second optical waveguides furthercomprises providing mutually asymmetrical waveguides.
 14. A method as inclaim 11 further comprising: providing at least one optical waveguide;providing at least one second optical waveguide; adapting the opticalcomponent to transmit at least one chosen wavelength; and opticallycoupling the at least one chosen wavelength from the at least firstoptical waveguide to the at least one second optical waveguide via theoptical component.
 15. A method as in claim 14 wherein providing the atleast one first optical waveguide and the at least one second opticalwaveguides further comprises providing mutually asymmetrical waveguides.16. A method as in claim 11 further comprising: providing at least onefirst optical waveguide providing at least one second optical waveguide;providing at least one second optical component, wherein the at leastone second optical component comprises: at least one second opticalsupergrating, wherein the at least one second optical supergratingcomprises at least one second quantized refractive index profile,wherein the at least one second quantized refractive index profile isadapted to exhibit an at least one second finite plurality of refractiveindexes adapted to generate an at least one second set of opticalcharacteristics in at least one spectral band; adapting the at least oneoptical component to affect at least one chosen wavelength; adapting theat least one second optical component to affect the at least one chosenwavelength; and optically coupling the at least one second opticalwaveguide to the at least one first optical waveguide via the at leastone optical component and the at least one second optical component,wherein the optical coupling controls intra-waveguide reflection.
 17. Amethod as in claim 11 further comprising: providing at least one firstoptical waveguide; providing at least one second optical waveguide;providing at least one third optical waveguide; providing at least onesecond optical component, wherein the at least one second opticalcomponent comprises: at least one second optical supergrating, whereinthe at least one second optical supergrating comprises at least onesecond quantized refractive index profile, wherein the at least onesecond quantized refractive index profile is adapted to exhibit an atleast one second finite plurality of refractive indexes adapted togenerate an at least one second set of optical characteristics in atleast one spectral band; adapting the at least one optical component toaffect at least one chosen wavelength; adapting the at least one secondoptical component to affect the at least one chosen wavelength;optically coupling the at least one second optical waveguide to the atleast one first optical waveguide via the at least one opticalcomponent; and optically coupling the at least one third opticalwaveguide to the at least one second optical waveguide via the at leastone optical component.
 18. A method as in claim 11 further comprising:providing an optical circulator; providing at least one first opticalwaveguide; providing a second optical waveguide; providing a thirdoptical waveguide; adapting the optical component to reflect at leastone chosen wavelength; and arranging the optical circulator to couplethe chosen wavelength from the second optical waveguide to the at leastone first optical waveguide and from the least one first opticalwaveguide to the third optical waveguide.
 19. A method as in claim 11further comprising: providing a plurality of optical detectors fordetecting at least one chosen wavelength affected by the opticalcomponent, wherein each of the plurality of optical detector outputs anelectrical signal corresponding to the chosen wavelength detected by theoptical detector; and coupling each electrical signal to processingelectronics.
 20. (canceled)
 21. A method of processing at least oneoptical signal comprising: providing at least one optical component,wherein providing the at least one optical component comprises:providing at least one optical supergrating, wherein providing the atleast one optical supergrating comprises providing a quantizedrefractive index profile, wherein the quantized refractive index profileis adapted to exhibit a finite plurality of refractive indexes adaptedto generate optical characteristics in at least one spectral band; andadapting the at least one optical component to affect the at least oneoptical signal.
 22. A method as in 21 wherein processing the at leastone optical signal further comprises adjusting optical power of at leastone wavelength component of the at least one optical signal.
 23. Amethod as in claim 21 wherein processing the at least one optical signalfurther comprises spatially separating at least one wavelengthcomponent.
 24. An optical component comprising at least one opticalsupergrating, wherein the at least one optical supergrating comprises abinary quantized refractive index profile, wherein the binary quantizedrefractive index profile is adapted to exhibit a finite plurality ofrefractive indexes adapted to generate a reflectance spectrum in atleast one spectral band.
 25. A method of monitoring the stability of anoptical system comprising: providing at least one optical component,wherein the at least one optical component comprises: at least oneoptical supergrating, wherein the at least one optical supergratingcomprises a quantized refractive index profile, wherein the quantizedrefractive index profile is adapted to exhibit a finite plurality ofrefractive indexes adapted to generate optical characteristics in atleast one spectral band; providing a plurality of optical detectors;providing processing electronics; and adapting the at least one opticalcomponent to affect at least one chosen wavelength component to interactwith the plurality of optical detectors.
 26. A programmable opticalcomponent comprising at least one optical supergrating, wherein the atleast one optical supergrating comprises a quantized refractive indexprofile, wherein the quantized refractive index profile is adapted toexhibit a finite plurality of refractive indexes adapted to generatespectral characteristics in at least one spectral band.
 27. Aprogrammable optical component as in claim 26 further comprising the atleast one optical supergrating adapted to change the spectralcharacteristics in the at least one spectral band.
 28. A programmableoptical component as in claim 26 further comprising the at least oneoptical supergrating adapted to change the quantized refractive indexprofile.
 29. A programmable optical component as in claim 26 furthercomprising at least one thermally responsive optical supergratingadapted to change spectral characteristics in response to thermalenergy.
 30. A programmable optical component as in claim 26 wherein theoptical supergrating is adapted to electro-optic tuning, magneto-optictuning, electro-strictive tuning, and/or magneto-strictive tuning.
 31. Aprogrammable optical component as in claim 26 wherein the opticalsupergrating is adapted to optical illumination tuning, mechanicalstraining tuning, and/or current injection tuning.
 32. A programmableoptical component as in claim 26 wherein the optical supergrating isadapted to electro-chromic tuning.
 33. A programmable optical componentas in claim 26 wherein the optical supergrating is adapted to opticalpolymer tuning.
 34. A programmable optical component as in claim 26wherein the optical supergrating is adapted to molecular reconfigurationtuning.
 35. A programmable optical component as in claim 26 wherein theoptical supergrating is adapted to mechanical reconfiguration tuning.36.-68. (canceled)
 69. An optical component comprising at least onetuneable optical supergrating, wherein the at least one tuneable opticalsupergrating comprises a quantized refractive index profile, wherein thequantized refractive index profile is adapted to exhibit a finiteplurality of refractive indexes adapted to generate spectralcharacteristics in at least one spectral band.
 70. An optical componentas in claim 69 wherein the at least one tuneable optical supergrating isadapted to change a quantized refractive index profile associated withthe at least one tuneable optical supergrating.
 71. An optical componentas in claim 69 wherein the at least one tuneable optical supergratingfurther comprises at least one thermally responsive optical supergratingadapted to change spectral characteristics in response to thermalenergy.
 72. An optical component as in claim 69 wherein the at least onetuneable optical supergrating is adapted to electro-optic tuning,magneto-optic tuning, electro-strictive tuning, and/or magneto-strictivetuning.
 73. An optical component as in claim 69 wherein the at least onetuneable optical supergrating is adapted to optical illumination tuning,mechanical straining tuning, and/or current injection tuning.
 74. Anoptical component as in claim 69 wherein the at least one tuneableoptical supergrating is adapted to electro-chromic tuning.
 75. Aprogrammable optical component as in claim 69 further comprising atleast one liquid crystal material and/or at least one optical polymermaterial.
 76. An optical component as in claim 69 wherein the at leastone tuneable optical supergrating is adapted to mechanicalreconfiguration tuning.
 77. An optical component comprising at least oneoptical supergrating, wherein the at least one optical supergrating isadapted to affect optical phase characteristics in at least one spectralband.
 78. An optical component as in claim 77 wherein the at least oneoptical supergrating is adapted to conform to at least one dimension.79. An optical component as in claim 78 wherein the at least one opticalsupergrating further comprises an optical supergrating adaptable toprogramming and/or tuning.
 80. An optical coupler comprising: theoptical component as in claim 79, wherein the optical component isadapted to affect at least one chosen optical wavelength; a firstoptical waveguide; and a second optical waveguide, wherein the secondoptical waveguide is optically coupled to the first optical waveguidevia the optical component.
 81. An optical dispersion controllercomprising: a first optical component, wherein the first opticalcomponent comprises the optical component as in claim 79, wherein thefirst optical component is adapted to affect a first chosen wavelength;a first optical waveguide; and a second optical waveguide, wherein thefirst optical waveguide is optically coupled to the second opticalwaveguide via the first optical component.
 82. An optical dispersioncontroller comprising: a first optical waveguide; a second opticalwaveguide, the second optical waveguide comprising: an optical componentas in claim 79, wherein the optical component is adapted to reflect atleast one chosen optical wavelength; a third optical waveguide; and anoptical circulator, wherein the optical circulator optically couples thefirst, second, and third optical waveguides.
 83. An optical wavelengthstability monitor system comprising: a first optical waveguidecomprising: an optical component as in claim 79, wherein the opticalcomponent is adapted to affect at least one chosen optical wavelength; aplurality of optical detectors, the plurality of optical detectorsadapted to receive the affected chosen optical wavelength and generate aplurality of electric signals; and an electronic processor electricallycoupled to the plurality of optical detectors, wherein the electronicprocessor is adapted to produce an electric signal from the plurality ofelectric signals.
 84. An optical wavelength monitor system as in claim83 further comprising an optical reflector.
 85. An optical couplercomprising: a plurality of optical components as in claim 79, whereinthe plurality of optical components is adapted to affect at least onechosen optical wavelength; a first optical waveguide; and a secondoptical waveguide, wherein the second optical waveguide is opticallycoupled to the first optical waveguide via the plurality of opticalcomponents, wherein the plurality of optical components are adapted toeffect a desired inter-waveguide and intra-waveguide coupling.